• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.474-478
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• 2018

For process safety, fire and explosion characteristics of combustible materials handled at industrial fields must be available. The combustion properties for the prevention of the accidents in the work place are flash point, fire point, explosion limit, and autoignition temperature (AIT) etc.. However, the combustion properties suggested in the Material Safety Data Sheet (MSDS) are presented differently according to the literatures. The accurate combustion properties are necessary to safely treatment, transportation and handling of flammable substances. In the chemical industries, n-ethylaniline which is widely used as a raw material of intermediate products and rubber chemicals was selected. For safe handling of n-ethyl aniline, the flash point, the fire point and the AIT were measured. The lower explosion limit (LEL)of n-ethylaniline was calculated using the lower flash point obtained in the experiment. The flash points of n- ethylaniline by using the Setaflash and Pensky-Martens closed-cup testers measured $77^{\circ}C$ and $82^{\circ}C$, respectively. The flash points of n-ethylaniline using the Tag and Cleveland open cup testers are measured $85^{\circ}C$ and $92^{\circ}C$, respectively. The AIT of the measured n-ethyl aniline by the ASTM E659 apparatus was measured at $396^{\circ}C$. The LEL of n-ethylaniline measured by Setaflash closed-cup tester at $77^{\circ}C$ was calculated to be 1.02 vol%. In this study, it was possible to predict the LEL by using the lower flash point of n-ethylaniline measured by closed-cup tester. The relationship between the ignition temperature and the ignition delay time of the n-ethylaniline proposed in this study makes it possible to predict the ignition delay time at different ignition temperatures.

• Journal of the Korean Society of Safety
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• v.32 no.1
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• pp.27-32
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• 2017

The experimental design methodology was applied in the real scale coal-fired boiler to predict the various combustion properties according to the operating conditions and to assess the coal plant safety. Response surface method (RSM) was introduced as a design of experiment, and the database for RSM was provided with the numerical simulation of the coal-fired boiler. The three independent variables, high heating value of coal (HHV), overall stoichiometry excess air ratio (OST), and burner-side stoichiometry excess air ratio (BST), were set to characterize the cross section averaged NOx concentration and temperature distribution. The maximum NOx concentration was predicted accurately and mainly controlled by BST in the boiler. The parabola function was assumed for the zone averaged peak temperature distribution, and the prediction was in a fairly good agreement with the experiments except downstream. Also, the location of the peak temperature was compared with that of maximum NOx, which implies that thermal NOx formation is the main mechanism in the coal-fired boiler. These results promise the wide use of statistical models for the fast prediction and safety assessment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1780-1785
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• 2016

This paper presents few case studies of state diagnosis of XLPE cables using very low frequency techniques. The power cables of 22.9kV which have installation fault were assessed using VLF technique in addition to other techniques like insulation resistance and DC voltage withstand test. From the experimental results, The dielectric loss($tan{\delta}$) values of degradation of the cable(joint, knife, needle) at $U_0$ were 5.839, 5.526 and 6.251, respectively and all values were "further study advised". VLF PD measurement was also found defective portion. These method was effective in defect to fault in the degradation of the cable. However, the breakdown did not occur in the degradation of the cable because of properties of XLPE insulation. Few case studies of using VLF $tan{\delta}$ diagnosis for fault are measured and analyzed. The $tan{\delta}$ values at $U_0$ were "further study advised" or "action required".

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1761-1766
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• 2016

In this paper, we investigated the fusing current of carbon fiber and thermal properties of carbon fiber and metal shielded cable due to over-current. The fusing current value for the metal-coated carbon fiber was 5.3A in 3K, 7.4K and 13.05A in 12K. And if it exceeds 50% of the fusing current was broken with a rapid voltage rise. In the case of carbon fiber shielded cable, the temperature of the PVC sheath increased somewhat in the allowable current range. However, the temperature of PVC sheath rapidly increased to $128.1^{\circ}C$ in the 2 time allowable current range. This value is $10^{\circ}C$ higher than the temperature of PVC sheath on the metal screen cable, because the resistance of the carbon fiber is high and heat transfer rate is slow.

• International Journal of Safety
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• v.4 no.2
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• pp.18-23
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• 2005

There are many electrical connections in the electric apparatus and most fires due to a fault contact result from a failure or misuse of electric apparatus and installation. The fault contact happens between electrical connections by the loose and the mechanical vibration. In this paper, we have investigated thermal and electrical properties of screwed electric contacts due to the mechanical vibration. The exciter was connected to a signal generator and power amplifier that provided the vibration frequency and amplitude. The vibration, temperature and voltage data were sent to a data acquisition system (DAQ). In the case that fault contact took place, the arc happened between the screwed electric contact and electric wire, heat due to the arc was transmitted to the adjacent insulators, for which the oxide could be generated more. In addition, a spark was generated and the insulator began to melt. Thus, the possibility of electrical fire became the highest in this case. Finally, when the fault contact takes place due to vibration, the hazard of an electric accident is very high.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.112-116
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• 2017

This study applied risk indexes to the disaster flow event occurred at Mt. Umyeon region in 2011. A 2D hydrodynamic model was employed to calculate flow characteristics, and the model was validated against two dam break flow problems conducted by Bellos and EU CADAM project. The model performance was shown to be satisfactory. In order to determine which index is more appropriate to assess the vulnerability of debris flow, 3 risk indexes (FII, FHR and VDI) were considered. It was found that VDI, which determines the risk level only by the velocity factor, consistently predicted the risk level corresponding to 6 because the velocity range was widely organized. However, in the case of FII and FHR, the risk was reasonably quantified due to combined consideration of significant factors of flow velocity and debris thickness. Therefore, FII and FHR are expected to be more accurate than VDI. However, two indexes still need to be improved to include major factors such as debris density or material properties.

• Fire Science and Engineering
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• v.22 no.4
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• pp.70-75
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• 2008

Recently, there are so many studies related safety of railway vehicle. But these studies are focused on the passenger car, metro system and high speed train. However, the leakage of hazardous materials may contaminate the environment and cause terrible damage to the ecology, even the human and properties. And so, Safety and security have been already established in many countries, currently they are investing lots of money on the development of technology to prevent accidents. Therefore it is necessary to make a systematic plan and develop safety specifications. In this study, we compared between domestic and international general oil tank car safety regulations for the hazardous materials, and prepare the basic for the making of systematic safety plans and safety regulations for the transport of hazardous materials by tank car.

• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.96-101
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• 2009

In this study, a risk-appearance frequency evaluation model for railway level-crossing accidents is developed with the frequency estimation based on the accident history. It follows the worldwide common safety management approach and reflects the operation conditions and accident properties of the domestic railway system. The risk appearance frequency evaluation process contains a development of accident scenarios by defining the system configurations and functions, and a frequency estimation of hazardous events based on the accident history. The developed model is verified with the accident history during 5 years('03-'07) for 3 hazardous events: 'Being trapped in level crossing(Hl)', 'Crossing during warning signal(H2)' and 'Breaking through/detouring the barrier(H3)'. This risk appearance frequency evaluation model will be combined with a consequence evaluation model so as to offer full risk assessment for the railway accident. The accident risk assessment will contribute to improving the safety management of the railway system.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.353-366
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• 2019

As social standards have been subdivided and specialized due to social development, the number of related laws has also increased gradually, resulting in problems of duplication or conflict within the laws. After collecting all the safety standards that exist in Korea's legislation, it is necessary to analyze the characteristics of safety standards to find duplicate or conflicting issues. In this study, the characteristics of safety standards were divided into structural parts and lexical parts by extracting common elements that appear in all safety standards and singular points that appear only in specific safety standards. As a result of the analysis, two structural properties of safety standard were found and four lexical features were derived. The impact of these characteristics on future systems for managing safety standards was also reviewed. Based on this study, when more structural and lexical features of safety standards are accumulated in the future, it is possible to develop efficient algorithms to collect and analyze safety standards, which will help solve the problem of duplication and conflict of safety standards in the law.

• Carbon letters
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• v.2 no.1
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• pp.27-36
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• 2001

The pack-cementation process is the method which is formed SiC coating layer to improve weak oxidation properties of CFRCs (carbon fiber-reinforced carbons). This method develops the anti-oxidation coating layer having no dimensional changes and good wetting properties. In this study to improve the oxidative resistance of the prepared 4D CFRCs, the surface of CFRCs is coated by SiC using pack cementation method. The mechanical properties of SiC-coated 4D CFRCs are measured by the 3-point bending test, and their ablation properties are investigated by the arc torch plasma test. From the results, it is found that both mechanical and ablation properties of SiC-coated 4D CFRCs are much better than bare CFRCs.